09 Dec 2010: Report

Refilling the Carbon Sink: Biochar’s Potential and Pitfalls

The idea of creating biochar by burning organic waste in oxygen-free chambers — and then burying it — is being touted as a way to cool the planet. But while it already is being produced on a small scale, biochar’s proponents and detractors are sharply divided over whether it can help slow global warming.

by dave levitan

It has an appealing symmetry to it: If we got ourselves into this climate mess by digging up and burning coal, maybe we can fix it by creating some more coal and putting it back into the ground.

That very idea, involving the charcoal-like substance known as biochar, has been both touted as a planet-saving climate change mitigator and then ridiculed as yet another tilt at the proverbial windmill. Biochar has been lumped in with other so-called geoengineering ideas like solar radiation management and ocean fertilization, but it carries ancillary benefits to agriculture that the other planetary experiments can’t claim. The last two years have seen a sharp rise in research indicating its technical potential, and while the world treads carefully around other geoengineering fixes, there are now dozens of companies already producing and selling biochar on a small scale. Is large-scale deployment really feasible, or is it time for a step back and to take a harder look at whether this is a technology worth pursuing?

Biochar is created using a process called pyrolysis. Organic waste such as wood chips, agricultural byproducts or switchgrass is burned in the presence of little or no oxygen, yielding oil, synthetic gas (known as

One study shows that 12 percent of global greenhouse gas emissions could be offset with biochar production.

syngas), and a solid residue resembling charcoal. In fact, it is charcoal, except that the point is not to burn it, but to bury it. The pyrolysis process can be tweaked, with “slow pyrolysis” yielding more biochar and less oil and gas, and a faster version — seconds rather than hours or days — lowering the biochar product and upping the bio-energy side of the equation. In some systems, the syngas and oil can actually be used as a fuel to run the pyrolysis reaction, meaning it requires no external energy source beyond the organic waste itself.

Proponents point to two completely distinct benefits to burying biochar. The first is the ability of biochar to store carbon in a stable form, preventing the CO2 from organic matter from leaking into the atmosphere, where it contributes to climate change. Biochar also enriches soil, which improves food security in developing countries and crop production almost anywhere. The details on the benefit to soil are still being researched, but in certain types of soil, burying biochar can improve crop yields by improving water retention and moderating the pH, or acidity, of the soils.

Creating biochar actually reduces CO2 in the atmosphere because the process takes a theoretically carbon-neutral process of naturally decaying organic matter and turns it carbon-negative: When plants decay, they emit CO2, which other plants eventually absorb, and the cycle continues. Biochar stabilizes that decaying matter and accompanying CO2 and puts it in the ground to stay for — potentially — hundreds or even thousands of years. This idea, with supposedly enormous potential to help slow global warming, has drawn an impressive array of supporters toward biochar. Among its most vocal proponents is James Lovelock, founder of Gaia theory, who has touted biochar as the way to save the planet. The hype elicited a predictable response in the other direction, including scathing columns by The Guardian’s resident environmentalist George Monbiot and warnings from organizations like the UK’s BiofuelWatch.

Cornell University

Cornell researcher Johannes Lehmann, a biochar advocate, says the industry should focus on getting pilot programs in place over the next several years.

The backlash came, perhaps, with good reason, as the claims arrived without the support of much strong science. That picture, though, has started to shift. One research group led by Johannes Lehmann at Cornell University recently showed that a full 12 percent of global greenhouse gas emissions could be offset with biochar produced from “sustainably obtained” biomass. In other words, using organic waste that doesn’t affect food production or soil conservation could take about 1.8 gigatons of carbon dioxide, methane, and other gases out of the atmosphere each year. Over a century, Lehmann estimates the total offset at 130 gigatons, an amount that would play a big part in helping bring CO2 concentrations down and slow the world’s rising temperatures and sea levels.

Darko Matovic, a professor of mechanical engineering at Queens University in Ontario, published his own analysis of biochar’s potential and also found it to be enormous. He contends that burning and burying 10 percent of the world’s biomass waste would sequester nearly five gigatons of carbon annually — more than the net 4.1 gigatons that human activity adds to the atmosphere each year. Humans emit roughly 28 gigatons of CO2 into the atmosphere each year, but much of that is taken up by vegetation and oceans.

“The idea of biochar is really attractive, and in my opinion it is the only viable way of removing carbon dioxide from the atmosphere,” Matovic says. He and Lehmann agree on the ability of biochar to play a big role in fighting catastrophic climate change; Lehmann says the discussion on potential is largely over, and over the next several years getting pilot projects at large scales — meaning, industrial-sized pyrolysis plants — off the ground is the priority for the field.

Of course, the important thing to remember is that these analyses show technical potential rather than realistic goals. The logistics of actually converting 10 percent or more of the world’s organic waste into biochar and burying the result are, at this point at least, incredibly daunting.

“There are a lot of analyses that still have to be done to prove the economic potential, the social potential, the logistical potential,” says Debbie Reed, executive director of the non-profit International Biochar Initiative. “How would we do this? How long would it take to deploy? How much money would it cost?”

David Keith, a professor at the University of Calgary and a geoengineering expert, thinks the save-the-planet hype of biochar falls apart when one looks into the details. “What does pure technical potential mean? It’s a meaningless concept,” he says. “The pure technical potential of lots of

One critic says that burning biomass instead of coal would make more sense than burying it.

things is big enough to solve the climate problem. What matters is the relative utility.”

Keith says that in order to reach the amounts of biochar needed to have an effect on global climate systems, massive amounts of organic material would have to be gathered in central locations. Once that is the case, burning the biomass as a replacement for coal in power plants would make far more sense than burying it, he says.

“Why bury reduced carbon that has all that energy? It’s just senseless, unless you were in a world that needed no energy... You want to make a fuel if you’ve got a lot of carbon and you’re in a world that needs fuels.” If we could eventually add carbon capture and sequestration technologies to those plants burning the biomass, Keith adds, then the resulting greenhouse gas benefit would be almost twice as large as that yielded by burying the biochar.

The biochar advocates disagree. Matovic noted in his paper that carbon capture and sequestration carries its own significant energy requirements, and the fact that it may take decades to bring the technology into commercial viability swings the emissions reduction equation back in favor of burying biochar.

And Matovic and Lehmann are not alone: Along with James Lovelock, NASA’s Jim Hansen has published on the potential of the idea. Hansen was among the targets of Monbiot’s column questioning the possibilities, but he responded that biochar is far from a “miracle cure” but could absolutely add some benefit to a range of climate mitigation strategies. UN officials have also argued for its potential, and the United Nations Framework Convention on Climate Change included it in recent documents as a potential sequestration tool. Also, a recent Natural Resources Defense Council report, though cautious in touting biochar’s benefits, calls for up to $150 million over eight years to start commercial-scale pilot projects.

Some biochar skeptics also bring up familiar problems in environmental circles. If adopted on a large scale, producing biochar eventually would be worth money in carbon trading schemes: Countries or

Unlike other geoengineering schemes, biochar is already happening and can be done on a local scale.

companies will pay others to burn large amounts of biomass in industrial-scale plants and bury the biochar produced as a way of offsetting their own emissions. If not properly regulated, though, there is the chance that those hoping to make money on biochar would displace food crops with switchgrass or even forests planted solely for the purposes of biochar production. The same problem has turned the considerable weight of the environmental movement almost completely against corn ethanol production.

Lehmann, of Cornell, says this problem can be avoided if the appropriate regulatory scheme is put into place. A trading mechanism could simply exclude biochar that results in indirect land use changes, where food products are displaced. With no way to profit on such schemes, Lehmann doesn’t think they would crop up. The corn ethanol story, though, as well as some other carbon trading missteps, suggests our regulatory decision-making isn’t always so perfect.

The potential problem with global biochar rollout is somewhat similar to those of solar radiation management (which involves injecting massive amounts of sulfates, like those from volcanic eruptions, into the stratosphere in order to cool the planet) or ocean fertilization (where we would dump huge quantities of iron into the oceans in order to absorb carbon dioxide from the air): Conducting experiments on a planetary scale may have unforeseen negative consequences, be they physical and chemical or more social, like indirect land use change. But there are significant differences: Biochar is already happening, and can be done on a more local scale.

As of yet, it is only happening on a small scale that even skeptics like Keith agree could be beneficial if done right. Even the small projects, though, are outpacing the need for a solid framework for the industry. Reed, of the International Biochar Initiative, says one of her group’s primary areas of focus in the coming year or two is on definitions, standards, and guidelines. If biochar is sold for use as a soil additive, buyers need to know exactly what they’re getting — was it slow or fast pyrolysis that made the product; what is the pH and other chemical properties; what types of soils would the specific product work best in, and so on.

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These standards can’t arrive soon enough: Reed says there are more than 120 companies already producing biochar or biochar-related products, including pyrolysis cook stoves. Most of the companies are located in the United States, such as Massachusetts-based New England Biochar, and are producing biochar for farms and gardeners or selling pyrolosis equipment. Although the number of companies involved continues to rise dramatically — including firms in Europe, Australia, and Brazil — there has been little indication of a profitable business model to this point.

As the commercial biochar field begins to take off, the idea is also now getting attention from policy makers that is either welcome or unwarranted, depending on one’s point of view. A recent report commissioned by U.S. Rep. Bart Gordon (D—Tenn.), chairman of the House committee on science and technology, also highlighted its potential for carbon sequestration. It acknowledges the “economic challenges” of large-scale development, but there is no hint yet that any regulatory framework to control the small but growing market in biochar technology.

“Some people fear that the right rules will never be in place, but you can always argue about that,” Lehmann says. “Just because someone might do the wrong thing, we can’t not do anything.”

Correction, Dec. 9, 2010: An earlier version of this story incorrectly stated the annual emissions of CO2 from human activity. The correct figure is roughly 28 gigatons per year.

COMMENTS

Biochar systems for Biofuels and soil carbon sequestration are so basically conservative in nature it is a shame that Republicans have not seized it as a central environmental policy plank as the conservatives in Australia have with their "Carbon sequestration without Taxes".

Given our election, the bipartisan potential that soil-C solutions hold to get climate legislation moving is more important than ever.

It's hard for most to revere microbes and fungus, but from our toes to our gums (onward), their balanced ecology is our health. The greater earth and soils are just as dependent, at much longer time scales. Our farming for over 10,000 years has been responsible for 2/3rds of our excess greenhouse gases. This soil carbon, converted to carbon dioxide, Methane & Nitrous oxide began a slow stable warming that now accelerates with burning of fossil fuel. So Biochar is more Reverse-Geo-Engineering.

Biochar viewed as soil Infrastructure; The old saw;
"Feed the Soil Not the Plants" becomes,
"Feed, Cloth and House the Soil, utilities included !".
Free Carbon Condominiums with carboxyl group fats in the pantry and hydroxyl alcohol in the mini bar. a fungi soil matrix that is a Highway for Moisture & nutrients and an Internet for plant chemical communication!
Build it and the Wee-Beasties will come.
Microbes like to sit down when they eat.
By setting this table we expand husbandry to whole new orders & Kingdoms of life.

Once thought through however, the elemental carbon nature of biochar understood, soil's reduced GHG emissions and the local economic stimulus perceived, then can be added that beyond rectifying the Carbon Cycle, biochar systems serve the same healing function for the Nitrogen & Phosphorous Cycles, Toxicity in Soils & Sediments and cut the carbon foot print of livestock by 1/2 with a 5%Char feed ration.

The production of fossil fuel free ammonia & char (SynGest, http://www.syngest.com/ ) and the 52% conservation of NH3 in composting with chars, are just the newest pathways for the highest value use of the fractionation of biomass.

Large Scale Scenarios;

Conservation Agricultural............ (+ Biochar = 100% CO2e Emissions )
"In general, soil carbon sequestration during the first decade of adoption of best conservation agricultural practices is 1.8 tons CO2 per hectare per year. On 5 billion hectares of agricultural land, this could represent one-third of the current annual global emission of CO2 from the burning of fossil fuels (i.e., 27 Pg CO2 per year)."
http://www.fao.org/ag/ca/doc/CA_SSC_Overview.pdf
Add just 1 Ton more of char/Ha (800lb/Ac) and you cover 100% Current Annual Fossil CO2 Emissions.

The Soil Carbon Standard committee's work with USDA, EPA and Congressional Ag committees offers real hope, with expansion to ISO status, the world can all be on the same soil carbon page.

Erich J. Knight
Chairman; Markets and Business Committee
2010 US BiocharConference, at Iowa State University
http://www.biorenew.iastate.edu/events/biochar2010/conference-agenda/agenda-overview.html

Posted by
Erich J. Knight
on 09 Dec 2010

I think the terms burning and burying give the reader the wrong impression with regard to how biochar is made and used.

'Burning' in it's usual common meaning "to undergo rapid combustion or consume fuel in such a way as to give off heat, gases, and, usually, light; be on fire" baking or heating the biomass is a better way to describe biomass to biochar using pyrolysis.

'Burying' in it's usual common meaning "to put in the ground and cover with earth" where 'mixing or blending with top soils gives the reader a much better picture of how biochar should be used.

Far and well written article apart from that.

Posted by
Barry Batchelor
on 09 Dec 2010

Thank you for an informative, thoughtful and balanced article. Rare in journalism these days -
you're to be commended.

Posted by
David Foley
on 10 Dec 2010

"Keith says that in order to reach the amounts of biochar needed to have an effect on global
climate systems, massive amounts of organic material would have to be gathered in central locations," which would be costly and energy-intensive.

Oh? That might be so if you think the only way to produce a massive effect is to create a
massive new industry. But there's no such need. This is not rocket science, and farmer cooperatives and/or local truckers would be more than able to handle it: So, why not mount biochar apparatus on flatbed trucks that move from farm to farm, pyrolizing waste on-site?Then nutrients can be returned to the very soil they came from—no shipping needed. Mobile facilities could also process manure from CAFOS that are currently polluting groundwater and creating health problems in so many places. Some biochar might need to be shipped to get where it's needed, but most would not. So overall, biochar could be a very energy-efficient enterprise, one that would generate many jobs and local business opportunities.

Now see how many problems the agricultural approach to biochar would solve, in both developed and less developed nations: —We'd be weaning farms off chemical fertilizers (made from oil, which is in finite supply, let's not forget);

—we'd be making soil less acidic;
—we'd be improving the soil's ability to hold water, which is good for crops and also for the
water table;
—we'd be mitigating serious pollution and illness associated with manure lagoons;
—and by improving the soil, we'd be enhancing not only food security, but also the nutritional
value of the food.

In short, biochar would be an important addition to world agriculture. AND—as a bonus—we'd be sequestering carbon at a very high clip. You wouldn't even need to create a system of carbon credits. Farmers would WANT to participate, for the sake of better yields and better health, and in time the practice of biochar would go viral. Paradoxically, it may be that
using biochar as a soil amender would be the fastest way to sequester massive amounts of
carbon.

And here's one more benefit: as produced by small pyrolyzing stoves, biochar is a technology that has promise to let the small tropical farmer stay on his land. In brief, you replace the traditional three-stone fire with a special stove (they're simple and can be locally made, generating a small business). While dinner gets cooked, the fuel turns into biochar, which can be blended with manure or compost (some form of treatment seems critical) and eventually put back on the fields. Also, the stoves draw the smoke back in and burn it. As a result, the cooks inhale a lot less smoke.

Posted by
Elise Hancock
on 13 Dec 2010

Of course the idea of biochar is attractive, because to some it looks like a way to avoid changing our carbon emission intensive development model.

However, the handbook: Biochar for Environmental Management: Science and Technology, edited by Johannes Lehmann and Stephen Joseph, Earthscan 2009 shows clearly that every major claim made for biochar still remains unproven, requiring further research.

Let's look at the first sentence: "If we got ourselves into this climate mess by digging up and burning coal, maybe we can fix it by creating some more coal and putting it back into the ground."

However, according to Jeffrey Duke, the fossil fuels burnt in 1997 alone were equivalent to 400 years of Net Primary Productivity (http://globalecology.stanford.edu/DGE/Dukes/Dukes_ClimChange1.pdf), which illustrates the absurdity of thinking we can match the world's coal consumption with new charcoal production.

Then there is the idea from Matovic, who is cited in the article, that we can offset all annual greenhouse gas emissions caused for which humans are responsible by mobilising 10% of the world's Net Primary Productivity (i.e. total global biomass growth). In an article for Nature Communications, several authors including Lehmann note that we would have to convert some 556 million hectares of land to the production of biomass raw materials to make the biochar necessary to do rather less than this - i.e. to reduce global greenhouse gas emissions by 12% a year. Residues, apart from being essential for other purposes, such as building up soil organic matter, are completely insufficient for this purpose. Furthermore, we still lack the proof that such action would actually work. (Woolf D, Amonette JE , Street-Perrott A, Lehmann J, Joseph S. Sustainable biochar to mitigate global climate change. Nature Communications 1(5), 1–9 (2010))

As noted, in the study cited in the article, Matovic calculates biochar potential as follows: that 10% of the world's Net Primary Productivity or NPP (i.e. all annual biomass growth) - a total of some 6 billion tonnes a year, could be mobilised to produce 3 billion tonnes of biochar. This just happens to be (according to Helmut Haberl's calculations
http://www.eoearth.org/article/Global_human_appropriation_of_net_primary_production_(HANPP) ) the entire amount of biomass harvested/cut/withdrawn - all of agriculture, all crops, crop residues, grazing, logging and other wood removal.

This would appear to require a sort of biochar dictatorship to implement and there is no proof that it would work as claimed. However, a major danger, as the writer notes, is that biochar will be embraced by the carbon markets to create offsets whether biochar works or not.

Posted by
Helena Paul
on 13 Dec 2010

A simpler way to reverse global warming is to plant billions of trees.

Posted by
TRB
on 14 Dec 2010

Except when the billions of trees eventually die, they will release all of their carbon back into the atmosphere. Better to plant billions of trees and, when they die, turn them to biochar and keep the carbon locked up, while enriching the soil. I think people don't work with trees much anymore. If you want a tree to sequester carbon, you must either build something with it before it rots or bury it in some way before it rots. If it rots, the carbon is released again.

The "Industrial scale" argument is hilarious. I mean, after all, when we burn oil, we don't ship it to industrial plants, to be burned and thereby transporting thousands of people at a time on huge conveyor belts. Oil, at least, is shipped to small, local-scale combustion facilities, known as engines. What's wrong with small, local-scale biochar retorts?

Posted by
KJMClark
on 14 Dec 2010

20 to 32% of potential NPP is now used, wasted or destroyed. In the last ten years Humans have consumed increasing amounts of the biosphere, 20% in 1995 to 25% in 2005 of the total generated on land.

NASA Data;
http://environmentalresearchweb.org/cws/article/news/44582

The total TERRESTRIAL NPP co-opted by humans is 40 G tons, certainly the fraction "used " has much lignins left to convert into char, the wasted & destroyed are prime for extraction of biofuel & char.

Biotic Carbon, the carbon transformed by life, should never be combusted, oxidized and destroyed. It deserves more respect, reverence even, and understanding to use it back to the soil where 2/3 of excess atmospheric carbon originally came from.

"Priority One"
by Allan J. Yeomans is a seminal work on top soil and how it can sequester enormous amounts of carbon. He parses all the numbers for you in chapter 5;

Oil, at least, is shipped to small, local-scale combustion facilities, known as engines. What's wrong with small, local-scale biochar retorts?

Posted by
jocuri online
on 18 Dec 2010

I heard about biochar a few months ago from a friend of mine. I never thought that something as simple as charcoal could do so much for the soil and the environment. I was amazed after reading "The Biochar Revolution" from http://biochar-books.com/The_Biochar_Revolution.

It was a great help in opening my mind to issues that affect us all.

Posted by
landboy09
on 19 Dec 2010

Hi All-
This article was well done showing a number of different views. I am a supporter of biochar and I also work with a biochar company- Biochar Engineering Corp. www.biocharengineering.com

The equipment and products we produce and sell now can be cost effective. To start this process we surely do not need to sequester GTs Carbon/year we just need to begin by taking step 1 of a 10 step path - without the first step we don't go forward.

One specific location were biochar production can be cost effective it the following: -- biochar production from MSW wood waste or wood products production - with thermal energy stream utilization onsite -- this gain value from the biochar and also from the thermal energy. I have seen char increase water holding capacity by 20-50% and decrease fertilization needs. This approach will decrease waste while increasing valuble products like thermal energy, in field water and nutrients.

I suggest if you are interested in biochar you find and buy 1 lbs - put it into one of your house plants and watch how it decreases the watering needs. The water holding advantages by them self may change farming in the western us. What is the value of a 25% decrease in water needs - on my 1 acre of Colorado vegetables that figure is significant as is the saved fuel from California imports.

regards
Jonah Levine
Jonah@biocharengineering.com

Posted by
Jonah G Levine
on 28 Dec 2010

What I would like to see is a new carbon narrative for a closed system, the planet earth,
that integrates all of: space conditioning, ocean acidity, soil health, the nutritional value of food,
and climate disruption with human health and well being.

Biochar, which I support, is, I suspect, a piece in the puzzle suggested above. It can be a part of a distributed economics for a closed system that leverages the full spectrum of local assets. Such an approach can accept the impossibility of perfect knowledge and thus avoid the traps of
central planning, which must at least suppose the possibility of perfectible knowledge.

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